This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Lithium (Li) is an attractive anode material with an extremely high capacity (3860 mA·h·g−1) and the lowest known negative potential (−3.040 V versus the standard hydrogen electrode). Problems arise, however, with dendrite formation during electrochemical cycling of the Li metal, which causes severe capacity fade and cell failure due to electrical shorting or electrolyte consumption. This longstanding problem has prevented the incorporation of Li anodes in commercial rechargeable cells because the useful lifetime of a Li battery (i.e. the number of times the battery can be charged) is unacceptably low.
Conventional technologies to prevent lithium dendrite growth have focused on improving stability of in-situ formed solid electrolyte interphase (SEI) layers through electrolyte additives, or by applying ex-situ (i.e. artificial) SEI layers to the lithium metal using physical vapor deposition (PVD) or chemical vapor deposition (CVD) methods that produce non-uniform coatings prone to pinholes and other defects. To compensate for these defects, thicker coatings are generally used (i.e. 10-100 μm); however, these thicker coatings increase cell impedance and reduce gravimetric and volumetric capacity.
Thus, a need exists for improved technology, including protective coatings for lithium anodes and methods of fabrication thereof.